Level weighing device

ABSTRACT

A weighing device (2) for accurately weighing an object, which includes a support base (4), a weighing platform (8) for supporting the object and a load cell (6) mounted on the base (4) for measuring the weight of the object. The load cell (6) includes an anchoring section (18) for anchoring the load cell (6) to the support base (4). The device further includes an inclinometer (28) horizontally positioned in correspondence with the anchoring section (18) of the load cell (6) for measuring the levelness of the load cell (6). A display means (32) is connected to the inclinometer (28) for conveying information necessary to obtain an accurate weight measurement.

FIELD AND BACKGROUND OF THE INVENTION

The present invention is related to a weighing device, and particularlyto a weighing device which includes an inclinometer. The invention isalso related to a method for accurately weighing an object.

It is well known that in order for a weighing scale to accuratelymeasure the weight of an object, it must be level. By the term `level`it is meant parallel with the plane of the horizon, or in other words,perfectly horizontal. The scale must be level because the load cell,which measures the load, only measures directly vertical forces appliedto it. If the force applied to the load cell is at an angle, only thevertical component of the force (the force x the cosine of the angle)will be measured.

In order to ensure the levelness of a scale, it is customary to includeon the surface of the scale a small liquid-filled transparent chamber orvial containing a bubble. A circle or other mark is located on thesurface of the chamber so that when the scale is level, the bubble ispositioned within the mark. The levelness of the scale can be adjusted,for example, by adjusting the lengths of the legs of the scale. Althoughthis method results in a level scale, it is quite time-consuming andinvolves much trial-and-error until the legs of the scale are adjustedto their proper lengths.

Tilt sensors or inclinometers are instruments, usually electrical orelectronic, capable of measuring quantitatively the angle of tilt of anobject and outputting the result to an appropriate display. Varioustypes of these instruments based on various physical principles such aselectrical resistance of a liquid or the displacement of a pendulum areknown. They are commonly installed in ships or aircraft, or used withconstruction lasers or vertical gyros.

It is an object of the invention to provide a weighing device which canbe levelled quickly and easily.

It is another object of the invention to provide a weighing device willgive an accurate weight measurement without being levelled.

It is a further object of the invention to provide a new type ofinclinometer.

SUMMARY OF THE INVENTION

In accordance with this invention there is thus provided a weighingdevice for accurately weighing an object comprising: a support base; aweighing platform for supporting the object; a load cell mounted on thebase for measuring the weight of the object, the load cell comprising ananchoring section for anchoring the load cell to the support base; aninclinometer horizontally positioned in correspondence with theanchoring section of the load cell for measuring the levelness of theload cell; and a display means connected to the inclinometer forconveying information necessary to obtain an accurate weightmeasurement.

In accordance with this invention there is also provided a method foraccurately weighing an object using the above weighing device.

By combining an inclinometer with a weighing scale, the levelling of thescale is greatly simplified and speeded up. In addition, it is possibleto integrate the output of the load cell and the inclinometer in aprocessor so that the weight measurement is automatically corrected forthe tilt of the scale, in which case the need to adjust the level of thescale is obviated.

In addition to the aforementioned types of inclinometers, a load cellcan be used in a similar manner to measure the tilt of an object. Theload cell can be calibrated to measure an internal weight (or its ownweight) while in a horizontal state. If the load cell is then tilted, itwill measure a weight less than the calibrated weight by a factorrelated to the cosine of the angle of tilt. This output can then be usedto indicate the degree of tilt.

Further features and advantages of the invention will be apparent fromthe description below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 is a schematic, exploded, perspective view of a prior artweighing scale;

FIG. 2 is a schematic, perspective view of one embodiment of theinvention; and

FIG. 3 is a schematic, perspective view of another embodiment of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1, there is illustrated a weighing device,generally designated 2, comprising a support base 4, a load cell 6mounted on the base, and a weighing platform 8 supported by the loadcell.

The base 4 is supported on four rotatable legs 10, each comprising athreaded rod 12 and a base element 14. The legs are threadedrespectively into four threaded holes 16 located at the corners of thebase 4. The heights of the corners of the base, and therefore itslevelness, are adjusted by the extent of the threading of the rods 12into the holes 16.

The load cell 6 includes two sections, an anchoring section 18 whichanchors the load cell to the base, and a load-bearing section 20 whichis attached to the weighing platform 8 for measuring the weight of theobject on the platform. The upper surface of the load bearing section 20projects slightly above the remainder of the load cell and its lowersurface does not rest on the base, so that it is free to bear the weightof the object. An electrical cord 22 transmits the weight measurement toa display means (not shown).

The weighing platform 8 rests on the load-bearing section 20 of the loadcell and is attached to it. The platform includes a levelling chamber 24for indicating the horizontal position of the platform.

FIG. 2 illustrates a weighing device 26 without the weighing platform.Mounted on the base 4, in addition to the load cell 6, is aninclinometer 28, in this case, another load cell calibrated as explainedabove. Both the load cell and the inclinometer are fixed to the supportbase 4 so that their horizontal positions are in correspondence one tothe other. It is to be understood that the same result is obtained bysecuring the inclinometer to the load cell rather than to the base.

Wires 30 extend from the load cell and inclinometer to a display means32 which has a first display 34 for displaying the weight measured bythe scale and a second display 36 for indicating which legs 10 of thebase should be threaded in which direction in order to bring the scaleto levelness. The first display 34 is connected to the load cell 6 andthe second display 36 is connected through a processor in the displaymeans to the inclinometer 28.

Referring now to FIG. 3, there is illustrated a weighing device 26 inwhich the load cell 6 and inclinometer 28, which is also a load cell,form one integral unit. This simplifies manufacturing and reduces costs.Both the load cell and the inclinometer are fixed to the base 4 by acommon anchoring section 18. A common cable 38 including wires from theinclinometer 28 and from the load-bearing section 20 of the load cellextends from the scale to a processor 40. The processor integrates theoutput from both devices and corrects the weight measured by theload-bearing section for inaccuracies due to any deviation of the loadcell from levelness as measured by the inclinometer. The correctedoutput is then transmitted to the display means 32 where the correctedweight is displayed on a display 34.

The above configuration can of course be used with a display means asillustrated in FIG. 2, and the configuration illustrated in FIG. 2 canbe used with the display means of FIG. 3. Furthermore, the inclinometercan be of any of the standard types, and not just of the load cell type.

While the present invention has been described in terms of two preferredembodiments, it is expected that modifications and improvements willoccur to those skilled in the art upon consideration of this disclosure.

What is claimed is:
 1. A weighing device is for determining an accurateweight of an object, the weighing device comprising:(a) a support base;(b) a weighing platform for supporting the object; (c) a first load cellattached to said support base and deployed to support said weighingplatform so as to provide an object weight measurement which isindicative of the weight of an object on said weighing platform; (d) asecond load cell, attached to one of said support base and said firstload cell, said second load cell being deployed so as to provide aninclination correction measurement which is independent of the weight ofthe object on said weighing platform; and (e) a processor electricallyconnected to said first and second load cells and configured to correctsaid object weight measurements by an inclination correction factorderived from said inclination correction measurement.
 2. The weighingdevice of claim 1, wherein said second load cell is attached to saidsupport base.
 3. The weighing device of claim 1, wherein said first andsecond load cells are implemented as one integral unit attached to saidsupport base at a common anchoring section.
 4. A method for determiningan accurate weight of an object, the method comprising:(a) measuring theweight of the object; and (b) correcting the weight by an inclinationcorrection factor, said inclination correction factor being derived froman output of a load cell deployed so as to be unaffected by the weightof the object.
 5. The method of claim 4, wherein said measuring isperformed using a second load cell.
 6. The method of claim 5, whereinsaid inclination correction factor is derived by comparing said outputwith an initial calibration value of said output measured with said loadcell ina horizontal position.
 7. An inclinometer for measuring smallinclinations from an initial orientation, the inclinometercomprising:(a) a load cell having a constant loading and being deployedso as to be level in the initial orientation; and (b) a processorelectrically associated with said load cell and configured for comparingand output of said load cell with an initial calibration value of saidoutput measured with said load cell level.